Implantable cardioverter defibrillators - the past, present and future

Connected to the cloud at time of death: a case report

BACKGROUND

Our case report provides the first clinical evaluation of autopsy practices for a patient death that occurs on the cloud. We question how autopsy practices may require adaptation for a death that presents via the 'Internet of Things', examining how existing guidelines capture data related to death which is no longer confined to the patient's body.

CASE PRESENTATION

The patient was a British man in his 50s, who came to the attention of the medical team via an alert on the cloud-based platform that monitored his implanted cardioverter defibrillator (ICD). The patient had a background of congenital heart disease, with previous ventricular fibrillation cardiac arrest, for which the ICD had been implanted two years earlier. Retrospective analysis of the cloud data demonstrated a gradually decreasing nocturnal heart rate over the previous three months, falling to a final transmission of 24 beats per minute (bpm). In the patient post-mortem the ICD was treated as medical waste, structural tissue changes precluded the effective evaluation of device hardware, potential issues related to device software were not investigated and the cause of death was assigned to underlying heart failure. The documentation from the attending law enforcement officials did not consider possible digital causes of harm and relevant technology was not collected from the scene of death.

CONCLUSION

Through this patient case we explore novel challenges associated with digital deaths including; (1) device hardware issues (difficult extraction processes, impact of pathological tissue changes), (2) software and data limitations (impact of negative body temperatures and mortuary radio-imaging on devices, lack of retrospective cloud data analysis), (3) guideline limitations (missing digital components in autopsy instruction and death certification), and (4) changes to clinical management (emotional impact of communicating deaths occurring over the internet to members of family). We consider the implications of our findings for public health services, the security and intelligence community, and patients and their families. In sharing this report we seek to raise awareness of digital medical cases, to draw attention to how the nature of dying is changing through technology, and to motivate the development of digitally appropriate clinical practice.

Chaos control in cardiac dynamics: terminating chaotic states with local minima pacing

Current treatments of cardiac arrhythmias like ventricular fibrillation involve the application of a high-energy electric shock, that induces significant electrical currents in the myocardium and therefore involves severe side effects like possible tissue damage and post-traumatic stress. Using numerical simulations on four different models of 2D excitable media, this study demonstrates that low energy pulses applied shortly after local minima in the mean value of the transmembrane potential provide high success rates. We evaluate the performance of this approach for ten initial conditions of each model, ten spatially different stimuli, and different shock amplitudes. The investigated models of 2D excitable media cover a broad range of dominant frequencies and number of phase singularities, which demonstrates, that our findings are not limited to a specific kind of model or parameterization of it. Thus, we propose a method that incorporates the dynamics of the underlying system, even during pacing, and solely relies on a scalar observable, which is easily measurable in numerical simulations.

Distinguishing Primary Prevention From Secondary Prevention Implantable Cardioverter Defibrillators Using Administrative Health and Cardiac Device Registry Data

Background

Administrative health data and cardiac device registries can be used to empirically evaluate outcomes and costs after implantable cardioverter defibrillator (ICD) implantation. These datasets often have incomplete information on the indication for implantation (primary vs secondary prevention of sudden cardiac death).

Methods

We used 16 years of population-based cardiac device registry and administrative health data from British Columbia, Canada, to derive and internally validate statistical models that predict the likely indication for ICD implantation. We used chart review data as the reference standard for ICD indication in the Cardiac Device Registry database (CDR; 2004-2012 [Cardiac Services BC]) and nonmissing indication as the reference standard in the Heart Information System registry database (HEARTis; 2013-2019 [Cardiac Services BC]). We created 3 logistic regression prediction models in each database: one using only registry data, one using only administrative data, and one using both registry and administrative data. We assessed the predictive performance of each model using standard metrics after optimism correction with 200 bootstrap resamples.

Results

Models that used registry data alone demonstrated excellent predictive performance (sensitivity ≥ 89%; specificity ≥ 87%). Models that used only administrative data performed well (sensitivity ≥ 84%; specificity ≥ 70%). Models that used both registry and administrative data showed modest gains over those that used registry data alone (sensitivity ≥ 90%; specificity ≥ 89%).

Conclusions

Administrative health data and cardiac device registry data can distinguish secondary prevention ICDs from primary prevention ICDs with acceptable sensitivity and specificity. Imputation of missing ICD indication might make these data resources more useful for research and health system monitoring.

Amiodarone and β-blocker combination therapy versus β-blocker monotherapy for ICD shock prevention: A meta-analysis

While implantable cardioverter-defibrillator (ICD) shocks are a lifesaving therapy, they can negatively affect the patient's quality of life. Amiodarone is commonly combined with β-blockers (BB) in ICD recipients. However, this combination therapy's efficacy in preventing shocks compared to standard BB monotherapy is not well studied. The aim of this systematic review and meta-analysis is to determine if combined amiodarone and BB therapy improves prevention of ICD shock delivery compared to BB monotherapy. We performed a comprehensive literature search using PubMed, Cochrane, and Web of Science databases, for studies that assess the impact of amiodarone and BB versus BB monotherapy in patients with an ICD. The primary outcome was a total number of ICD shocks delivered by the end of the study period. Four studies: three retrospective studies and one randomized controlled trial (RCT), with a total of 5818 patients with ICDs, were included in the analysis. Follow-up periods ranged from 1 to 5 years. The combined amiodarone and BB group was not associated with a significantly lower number of ICD shocks compared to the BB monotherapy group (OR, 0.76; 95% CI, 0.44-1.31; P = .32). A combination therapy of amiodarone and BB was not associated with any further reduction in ICD shocks, hospitalizations, or mortality. Additional RCTs are recommended to further validate our findings.

In Vivo Durability of Polyurethane Insulated Implantable Cardioverter Defibrillator (ICD) Leads

The 6935M Sprint Quattro Secure S and 6947M Sprint Quattro Secure are high voltage leads designed to administer a maximum of 40 joules of energy for terminating ventricular tachycardia or ventricular fibrillation. Both leads utilize silicone insulation and a polyurethane outer coating. The inner coil is shielded with polytetrafluoroethylene (PTFE) tubing, while other conductors are enveloped in ethylene tetrafluoroethylene (ETFE), contributing to the structural integrity and functionality of these leads. Polyurethane is a preferred material for the outer insulation of cardiac leads due to its flexibility and biocompatibility, while silicone rubber ensures chemical stability within the body, minimizing inflammatory or rejection responses. Thirteen implantable cardioverter defibrillator (ICD) leads were obtained from the Wright State University Anatomical Gift Program. The as-received devices exhibited varied in vivo implantation durations ranging from less than a month to 89 months, with an average in vivo duration of 41 ± 27 months. Tests were conducted using the Test Resources Q series system, ensuring compliance with ASTM Standard D 1708-02a and ASTM Standard D 412-06a. During testing, a load was applied to the intact lead, with careful inspection for surface defects before each test. Results of load to failure, percentage elongation, percentage elongation at 5 N, ultimate tensile strength, and modulus of elasticity were calculated. The findings revealed no significant differences in these parameters across all in vivo exposure durations. The residual properties of these ICD leads demonstrated remarkable stability and performance over a wide range of in vivo exposure durations, with no statistically significant degradation or performance changes observed.

Unusual migration of implantable cardioverter defibrillator that clinically mimicking breast cancer: A case report

Pacemaker and implantable cardioverter defibrillator migration to the breast are an extremely rare complication. The rarity of this phenomenon and its potential to mimic breast cancer emphasize the importance of reporting such cases. This study presents a rare migration of the device to the breast tissue that clinically mimicked breast cancer. This case underscores the need for comprehensive diagnostic approaches and individualized management strategies when faced with such clinical challenges. A 59-year-old female patient complained bilateral breast masses for a 3-month duration. She is a known case of diabetes mellitus and hypertension. In 2015, she underwent Implantable cardioverter defibrillator implantation for dilated cardiomyopathy and left ventricular failure. On examination, there was a skin dimpling in the left upper quadrant of her breast. The skin dimpling was clinically suspected to be breast cancer. Mammography showed an implantable cardiac device in the upper central part extending into the glandular parenchyma. A consultation with a cardiologist confirmed that the ICD was functioning properly, and as a result, no medical interventions were deemed required. Implantable cardioverter defibrillator migration to the breast is an extremely rare phenomenon and represent a complex clinical challenge that require a comprehensive diagnostic approach and individualized management strategies.

Evolution of Pacemakers and Implantable Cardioverter Defibrillators (ICDs) in Cardiology

Pacemakers and implantable cardioverter defibrillators (ICDs) have revolutionized cardiology by providing life-saving interventions for patients with cardiac rhythm disturbances. Pacing the heart is an effective treatment for people suffering from bradycardia caused by sinus node dysfunction or atrioventricular (AV) block, and electronic pacing has saved countless lives since its introduction into clinical practice. AV synchronization is the typical cycle of atrial depolarization and contraction followed by ventricular depolarization and contraction. The continuation of this cycle leads to appropriate ventricular filling and cardiac output. By contrast, the failure of the cycle results in AV asynchrony, which may result in heart failure. Cardiac resynchronization treatment (CRT) involves using customized pacemakers with or without implantable cardioverter defibrillators and tries to resynchronize the failing heart by enhancing myocardial contraction without increasing energy consumption. This review delves into the extensive journey of pacemakers and ICDs in the field of cardiology. It highlights the transformative impact of these devices on patient care and quality of life, emphasizing technological advancements, clinical applications, and prospects. This comprehensive review aims to provide insights into the dynamic landscape of cardiac rhythm management.

5G Service and Pacemakers/Implantable Defibrillators: What Is the Actual Risk?

Rapidly growing worldwide, 5G service is expected to deeply change the way we communicate, connect and share data. It encompasses the whole spectrum of new technology, infrastructure and mobile connectivity, and will touch not only every sector in the industry, but also many aspects of our everyday life. Although the compliance with international regulations provides reasonable protection to public health and safety, there might be specific issues not fully covered by the current technical standards. Among the aspects that shall be carefully considered, there is the potential interference that can be induced on medical devices, and in particular on implantable medical devices that are critical for the patient's life, such as pacemakers and implantable defibrillators. This study aims to assess the actual risk that 5G communication systems pose to pacemakers and implantable defibrillators. The setup proposed by the ISO 14117 standard was adapted to include 5G characteristic frequencies of 700 MHz and 3.6 GHz. A total number of 384 tests were conducted. Among them, 43 EMI events were observed. Collected results reveal that RF hand-held transmitters operating in these two frequency bands do not pose additional risk compared to pre-5G bands and that the safety distance of 15 cm typically indicted by the PM/ICD manufacturer is still able to guarantee the patient's safety.

Automatic daily remote monitoring in heart failure patients implanted with a cardiac resynchronisation therapy-defibrillator: a single-centre observational pilot study

INTRODUCTION

The impact of remote monitoring (RM) on clinical outcomes in heart failure (HF) patients with cardiac resynchronisation therapy-defibrillator (CRT-D) implantation is controversial. This study sought to evaluate the performance of an RM follow-up protocol using modified criteria of the PARTNERS HF trial in comparison with a conventional follow-up scheme.

MATERIAL AND METHODS

We compared cardiovascular (CV) mortality (primary endpoint) and hospitalisation events for decompensated HF, and the number of ambulatory in-office visits (secondary endpoint) in CRT-D implanted patients with automatic RM utilising daily transmissions (RM group, n = 45) and conventional follow-up (CFU group, n = 43) in a single-centre observational study.

RESULTS

After a median follow-up of 25 months, a significant advantage was seen in the RM group in terms of CV mortality (1 vs. 6 death event, p = 0.04), although RM follow-up was not an independent predictor for CV mortality (HR = 0.882; 95% CI: 0.25-3.09; p = 0.845). Patient CV mortality was independently influenced by hospitalisation events for decompensated HF (HR = 3.24; 95% CI: 8-84; p = 0.022) during follow-up. We observed significantly fewer hospitalisation events for decompensated HF (8 vs. 29 events, p = 0.046) in the RM group. Furthermore, a decreased number of total (161 vs. 263, p < 0.01) and unnecessary ambulatory in-office visits (6 vs. 19, p = 0.012) were seen in the RM group as compared to the CFU group.

CONCLUSIONS

Follow-up of CRT-D patients using automatic RM with daily transmissions based on modified PARTNERS HF criteria enabled more effective ambulatory interventions leading indirectly to improved CV survival. Moreover, RM directly decreased the number of HF hospitalizations and ambulatory follow-up burden compared to CRT-D patients with conventional follow-up.